I had no idea loons did this. I photographed a pair of loons chasing each other up and down little long pond one morning at sunrise. They did this for about 15 minutes straight, just zooming up and down the lake. At first I thought they were young loons just kind of playing, but later I learned it was a territorial thing. An interloper was being chased off by half of a mated pair.
Photographed with Nikon Z8 and Sigma 150-600mm Contemporary lens at ISO 900, 60mm f/6.3, 1/500. Very little processing done other than AI noise reduction through Lightroom.